The car belongs to my 31 year old son. Oil is Mobile 1 synthetic. Changed every 3-4K. Update on cost so far valve Job $60, surface heads $30, spring pressure test $40, top end gasket set $250.00, new lash adjusters $60, Head Bolts $43, Main chain tenisoner$ 58.52, Tax $38. Now I have to get the bottom end cleaned and that means new counter balance bearings, and a bottom gasket set, probably another $200. I can't imagine what a dealer would charge!. I'll try to take some more photos and post

Wow.....don't know how I missed this thread. I am sorry that you guys are having problems.

Am I reading this right??? This 02 KJ was bought new and using Mobil 1 every 3-4,000 miles and the motor is sludged up causing damage??

I would think if the KJ was bought used and the prior owner really abused it by not changing the oil, this would happen. I actually know someone who does not do any oil changes at all and just gets a new lease every year. I pity the poor person that gets his vehicles. It is a shame that there are people that do things like that. Then someone comes along and buys it and has problems.

Just to let you know, we are a Jeep Family. My older son has the 2002 Liberty, My youngest boy has a 98 Cherokee with 6"lift and 33 AT and I have a 2003 Rubicon with 4" lift and 33 MTZ. We love to go trail ridding at Uwarrie National Forrest. My oldest wants to lift his liberty, tha is once it is put back together

Another photo of bottom. The head had so much sluge that ihad to dig out the sludge on the right rear to get to the head bolt. I can't believe it either. I ask him at least 4 times if he is sure he changed the oil and he swears he did. Yes, I live in the town Dale Earnhardt was from in NC.

The PCV and breathers were repaced when the rocker was a year ago but the damage was probably already don by then. I have heard of places charging for an OIL change and not doing it. I ask my son where he took it. ai thnk it was one of the quick change places.

I have heard of places charging for an OIL change and not doing it. I ask my son where he took it. ai thnk it was one of the quick change places.

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Then i'd be willing to bet thats the cause right there. On youtube is the investigation of one of those quickie lube places, and it was unreal the amount of "murder" they were getting away with. Scamming people into replacing things that dont need it, claiming to change the oil and not, claiming to replace those parts they just scammed them into and not doing it...etc etc.

I ask my son where he took it. ai thnk it was one of the quick change places.

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Thats not good at all.

Wonder if this could have anything to do with the condensation building up in the filler tube? Ive never seen it, but Ive seen some pics of some bad build up. Think thats just isolated to the filler neck or that means there is alot of condensation in the engine?

The PCV and breathers were repaced when the rocker was a year ago but the damage was probably already don by then. I have heard of places charging for an OIL change and not doing it. I ask my son where he took it. ai thnk it was one of the quick change places.

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That is the problem. DO NOT USE those places. They are NOT GOOD. My GF had an absolutely horrible experience with one of those places. I won't get into it and start a rant...... Sorry. I get upset just thinking about it.

I do all mine myself. When I can't (like it's 5 degrees out- - or something I can't do) I take it up the street to a trusted independant shop and they are honest. No one touches mine except me or Rick unless it's a warrenty thing and I have to bring it to the dealer.

Please find a good local independant garage.

Even if you were using Dino and changing at 3-4,000 mile intervals, that motor should be pretty clean inside. I have not heard about any sludge problems with the 3.7L anyway. It has been in use long enough and if this were the case we and everyone elce would be having issues with it.

Anyway, I am sorry for your problems with it and let us know how you make out with it.

I don't know... But it sounds like vehicle abuse to me.
I have never known anybody including myself to have that many problems when a vehicle is driven properly. Only when rat bagged and abused does one suffer problems like that.

There's a snappy new moniker for Black Death now, and it's called sludge. The cause is the same as Black Death and it seems to be regardless of maintenance or mileage. The chemical compounds in engine oils break down over time due to prolonged exposure to high temperatures and poor maintenance habits. When the oil oxidises, the additives separate from the oil and begin to chemically break down and solidify, leading to the baked-on oil deposits turning gelatinous, and that nasty compound is what is lovingly referred to nowadays as sludge. It's like black yoghurt. What doesn't help is that modern engines, due to packaging, have smaller sumps than in the "good old days" and so hold less oil. This means that the oil that is present in the engine can't hold as much crap (for want of a better word) and can lead to earlier chemical breakdown.
The most common factor in sludge buildup is mineral oils combined with a lack of maintenance by the car owner combined with harsh driving conditions. But this isn't true in all cases. For some reason, a 2005 Consumer Reports article discovered that some engines from Audi, Chrysler, Saab, Toyota, and Volkswagen appear prone to sludge almost no matter how often the oil is changed.

Abuse breaks things, there is no excessive blow by. I did a leakdown and compression test and all was in spec. There is very little wear on the engine. It still has the factory hone marks on the cylinder walls. The guy at the machine shop says he sees very few 3.7 L Chrysler engines go through which speaks well for the engine. The only thing that causes sludge is not changing the oil, running the engine to cold by doing short trips with a lot of stop and go driving or poor engine design. I think poor design can probably be ruled out. In that my son is not a liar, I believe he paid to have the oil changed. If the lube shop changed it uor not I don't know. He does a lot of short trips so , I believe that is the likely cause. I think we have beat this enough. If you want to see some photos after I get the engine back together I will be happy to post, otherwise this will be my last post. I see no farther value in continuing the debate

The 3.7 does not have valve train problems. They have made over a million 3.7L's so you would hear about it alot more if they did have issues.

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You are right jeepjeepster,actually there are well over 1.5 million 3.7's around,more then just the KJ/KK use them.

With mass prodution your going to have some bad ones,a few here and a few there is not a problem with the whole lot of them.I've heard those stories before from other dealers that go like this---" Oh we just did 3 or 50000 of those,that's a common problem"---yeah right,if you believe that I've got some beach front property in South Dakota to sell you.also think that the 4.7 V-8 shares the same valvetrain and there is no problems with them,sure your going to have some failures but overall not a common problem.Most engine failures today are about 90% owner's fault,neglect or abuse,just because you change the oil doesn't mean nothing,there is way more involved then that.The other 10% is metal fatigue and it was going to break no matter what,hey it happens,get over it.The type of oil you use and the filter can make a drastic difference,YES there is bad oils and filters,Jiffy Lube only sells bad oil and filters.With the advent of emission regulations that forced the auto makers to make the engines more efficent,the engine temps increased and the tolerances got tighter,then the fuel got worse(unleaded fuel),all this equals more engine failures.Theres a reason the old muscle cars ran at 160 degrees and had looser tolerances,the engines lasted longer,but mpg's and emissions where terrible.There are alot of KJ's(even Dodge Ram pickups with the 3.7) that are well over 100,000 miles,over on L.O.S.T. a guy has a '02 KJ with over 200,000 miles and only had to rebuild the tranny.And then theres the million+ 4.7 V-8's out there with over 100,000 and alot over 150,000 miles and going strong.